Recovery of ethyl chloride from ethyl chloride-butane mixtures



March 3, 1942.

c. N. KIMBERLIN RECOVERY OF ETHYL CHLORIDE FROM ETHYL CHLORIDE-BUTANE MIXTURES Filed NOV. 5, 1939 (2A F'F/Nfl TE LINE i04 WENT LINE 7325 TING TOWER Exrvzkmr LIA/4E SOL ENT 'RA'GOVEZY ETHYL CHLDRIDE OuTLET SOLVENT LINE SOLVEN JTORAGE Patented Mar. 3, 1942 2,275,151 RECOVERY OF ETHYL CHLORIDE FROM ETHYL CHLORIDE -BUTANE MIXTURES Charles N. Kimberli'n,.Baton Rouge, La., assignor to Standard Oil Dev poration of Delaware elopment Company, a cor- Application November 3, 1-939, Serial No. 302,752

The invention is especially concerned with a method for the recovery of ethyl chloride, particularly for the recovery of ethyl chloride from its azeotropic mixture with butane. Such mixtures are obtained in the manufacture of tetraethyl lead. In accordance with the present invention, ethyl chloride is separated and recovered from butane by treatment with a suitable sol vent.

It is known in the art to prepare tetraethyl lead by various processes. A current procedure for the preparation of this compound is to react ethyl chloride with lead under suitable operating conditions. This may be accomplished by treating a sodium lead alloy with an excess of ethyl chloride at pressures upto about 100- pounds per square-inch and at temperatures in the range from 30 C. to 80 0., preferably in the presence of a catalytic substance such as pyridine or ethyl bromide. Upon completion of the reaction, which may require several hours, the tetraethyl lead is separated from the mixture and the unreacted materials are recovered in so far as possible. by any suitable means, usually by distillation. However, the complete recovery of the unreacted ethyl chloride is diflicult due to the fact that a relatively large quantity of normal butane is formed in a side reaction, which butane forms an azeotropic mixture with the unreacted ethyl chloride. The loss of this unreacted ethyl chlo ride associated with the butane the cost of the ethylation process and various processes have been directed for the recovery of the same.

I have now discovered a process by which the unreacted ethyl chloride may be fully and readily recovered. The process of my invention com.- prises treating the mixture of ethyl chloride and normal butane with a selective solvent having a preferential selectivity for the ethyl chloride as compared to butanes and the like. The solvents of my invention comprise alcohols, particularly aqueous solutions of alcohols. The process of my invention may be readily understood by reference to the, attached drawing illustrating one modification of the, same.

A mixture comprising. ethyl chloride and normal butane secured in the ethylation of lead with ethyl chloride is introduced into countercurrent treating tower I by means of feed line 2. This mixture flows upwardly through tower I and contacts a downfiowing solvent which is introduced into tower I by means of solvent feed 3. For that the line purposes of description, it is assumed materially raises rafiinate phase or relatively solvent poor phase solvent is a mixture of ethyl alcohol and substantially free of ethyl chloride is withdrawn from tower I by means of. line 4 and passed into solvent recovery unit 5, whereinthe solvent is removed from the butane, preferably by distillation. The butane is removed from solvent recovery unit 5 by means of line 6; while the butane free solvent is removed by means of line I and recycled to solvent storage 8. The solvent extract free of butanes containing the dissolved ethyl chloride is removed from solvent treating tower I by means of line 9 and passed into solvent recovery unit l0 which is preferably a distillation unit. The ethyl chloride is removed by means. of line. H. and recycled to the ethylation plant, while the ethyl chloride free solvent is removed from unit I0 by means of line I2 and re-, cycled to solvent storage 8. It is to be understood that the selectivity and' solvent power of the selective. solvent may be modified by the addition of anti-solvents which are introduced into the system by means of lines I3, I 4, I5, and I6 respectivelyt Treating tower I may also be provided with added heating and cooling means in order to maintain a temperature gradient throughout the tower.

A preferred modification tion is to utilize as the selective solvent ethyl alcohol. The solvent extract comprising ethyl alcohol. and the dissolved ethyl chloride is removed from. solvent treating tower I by means of line I! and then introduced into reaction vessel. I8T The solvent extract is then treated with of the present invenhydrogen chloride or an equivalent. agent which is introduced into vessel I8 by means of line l9 under conditions to convert the ethyl alcohol into ethyl chloride. The reaction. product comprising ethyl chloride and the dissolved ethyl chloride is then withdrawn from unit I8 and re- ;urned to the ethylation plant by means of line The process of the present invention may be widely varied. The process may be adapted for the removal of ethyl chloride from butane and ethyl chloride mixtures varying widely in composition. However, the invention is particularly applicable in the removal of ethyl chloride from azeotropic mixtures of butane and ethyl chloride be construed as limiting the same in any manner whatsoever:

Example Azeotropic mixtures of butane and ethyl comprising about 30% butane and about 20% 5 chloride were solvent treated at atmospheric ethyl chloride- Thus, the preferred Operation for pressure in accordance with the present invention the manufacture of tet e y l ad is 1' remove with solvents comprising ethyl alcohol and various the excess ethyl chloride containing the butane percentages of water. The results of these opfrom the ethylation unit and to distill the same, era-tions were as follows:

Feed Extract Rafl'inate Ethyl S lvent C0111 osii ii s til Ethyl tion p vol. 80%butane, Temp Ethyl Ethyl Vent free gggi used 2gziioertilgl chloride' Butane chloride Butane extract 90% C2H5OH }100 Pts.by gi0 Ptabylgol. Hala 01. Ptabygol. Pts. 0114;01- Percleggzt5 Percegst.

removing as a bottoms ethyl chloride and. re- The process of the present invention is not to moving as an overhead an azeotropic mixture be limited by any theory or mode of operation, of ethyl chloride and butane. The overhead mix- 25 but only by the following claims in which it is ture is then condensed and solvent treated in desired to claim all novelty in so far as the prior the manner described for the complete recovery art permits. of the ethyl chloride. I claim:

Any solvent which has a preferential selectiv- 1. Process for the separation of ethyl chloride ity for ethyl chloride as compared to butane may from a mixture comprising ethyl chloride n be used. Suitable solvents are, for example, butane comprising contacting said mixture with methyl alcohol, ethyl alcohol, isopropyl alcohol, an alcohol, separating the resulting phases and or mixed alcohols. Poly-hydroxy alcohols such removing the alcohol therefrom. as ethylene glycol or propylene glycol are also 2. Process for the separation of ethyl chloride suitable. The preferred solvents are those alfrom a mixture comprising ethyl chloride and cohols which have from one to four carbon butane comprising contacting said mixture with atoms in the molecule. Especially desirable 501- an aqueous solution of an alcohol, separating the vents are aqueous solutions of alcohols, particresulting phases and removing the alcohol and ularly a solvent comprising from 50% to 80% water therefrom. ethyl alcohol and from 50% to 20% water. 3. Process for the separation of ethyl chloride The operating conditions will vary widely, defrom a mixture comprising ethyl chloride and pending upon the particular solvent or solvent butane comprising contacting said mixture with mixture being employed, as well as upon the an aliphatic alcohol containing from one to four character of the feed material. In general, the carbon atO-ms in the molecule, separating the temperature of extraction when employing resulting phases and removing the alcohol thereaqueous solutions of alcohols having from one from. to four carbon atoms in the molecule is prefer- 4. Process according to claim 1 in which the ably in the range from about 15 C. to about alcohol is ethyl alcohol. 30 C. Under certain conditions, however, the 5. Process according to claim 2 in which the temperature may be as low as 10 C. or as aqueous solution of the alcohol comprises from high as 100 C. The pressure employed is suf- 50% to 80% ethy a o and 5 to 20% ficient to maintain the materials in the liquid Wate phase and l depend t large t t upon 6. Process in accordance with claim 2 in which the temperature of the operation. In general, the aqueous alcohol comprises about ethyl the pressure is in the range from about atmosalcohol and about 30% waten pheric pressure to about 200 pounds per square Procesjs for the reljqvery of ethyl fzhlonde inch or higher. from a mixture comprising ethyl chloride and The volume of solvent used per volume of feed ggz i gi z fiifi fg i i gzg ig i gg' zzg' being. extracted hkewls? may Vary prising contacting said mixture of ethyl chloride pefldmg upon the parmcular solvent or fl and butane at a temperature in the range of from mlxture F general when empbym? F about -10 c. to about 30 0. at a pressure sufsolvent comprising ethyl alcohol and water, 1t 15 fici t to maintain the materials in the liquid preferred to use from one to foul Volumes of phase with an aqueous solution of an aliphatic solvent mixture per volume of stock being treated.

In order to further illustrate the invention, the following example is given which should not alcohol containing from one to four carbon atoms in the molecule, separating the resulting phases and removing the alcohol and water therefrom. CHARLES N. KIMBERLIN. 

